Try again, if your build per the IBC or IRC.
I forget what the minimal sized Single Family Residence SFR requirements mandate, but it is close to 1075 SF with all utilities (Elec, HVAC, Plumbing, Sewer). Figure a min of $40k-$66k on permits alone plus utility hookups.
Least expensive solution is generally on an over 40 Acre parcel where zoning is relaxed, but distances to run utilities creep up on you.
Codes and regulations force everybody to live like 3rd world kings.
It does not have to be that big. It’s not a single family residence. And by the way people used to raise families in 800 sf homes. These, however have a different purpose. They are auxillary spaces to the main home.
You can build one to code for a lot less than that. Yes, regulations and fees cost a lot, which is part of the homelessness problem in the first place.